SARS-CoV-2 infection diagnosed only by cell culture isolation before the local outbreak in an Italian seven-week-old suckling baby.

Abstract SARS-CoV-2 is emerged in China on December 2019 and now declared pandemic by WHO. We describe the case of an Italian 7-week-old suckling baby SARS-CoV-2-positive only by cell culture method with no clinical suspicion and/or risk factors of SARS-CoV-2 infection. The patient was referred to the hospital with signs and symptoms of infection of the upper respiratory tract before the virus was spread to the province. Nasal and pharyngeal swabs and a nasopharyngeal aspirate were used for conventional and molecular diagnostic assays not including SARS-CoV-2 virus. Bacteria referred to resident population were revealed in nasal and pharyngeal swabs. No viruses were detected using both immunofluorescence assay and nucleic acid amplification assays in the nasopharyngeal aspirate. The baby was discharged in good conditions after 3 days of hospitalization. Later a cytopathic effect on the cell monolayers currently used for respiratory viruses was observed and the viral particles were identified as Coronaviridae by transmission electron microscopy. SARS-CoV-2 was identified by RT-PCR performed both on cell culture and on the stored aliquot of the original sample. The virus isolate was named SARS-Cov-2/human/Parma/1/2020.Cell culture still remains the only reference diagnostic method also for emerging viruses, allowing to reveal cytopathogenic viruses and demonstrating their infectivity.